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Sequence and Stereoselectivity of the C1-Symmetric Metallocene Me2Si(1-(4,7-Me2Ind))(9-Flu)ZrCl2

Wendy Fan, Robert M. Waymouth

Open publisher page 19 citations

Abstract

The homo- and copolymerization behaviors of two C 1 -symmetric metallocenes Me 2 Si(Ind)(9-Flu)ZrCl 2 ( 2 ) and Me 2 Si(1-(4,7-Me 2 Ind))(9-Flu)ZrCl 2 ( 3 ) in the presence of methylaluminoxane (MAO) are compared. In liquid propylene at 0 °C, metallocene 2 yields a predominantly isotactic polypropylene of low tacticity ([mmmm] = 27%) where metallocene 3 produces syndiotactic polypropylene (74% [rrrr]). The stereoselectivity of metallocene 3 depends on monomer concentration: the percentage of syndiotactic pentads [rrrr] in polymers derived from 3 increases with increasing monomer concentration. Copolymerization of ethylene and propylene with metallocenes 2 and 3 yields highly alternating but atactic ethylene−propylene copolymers.

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What this paper is about

The homo- and copolymerization behaviors of two C 1 -symmetric metallocenes Me 2 Si(Ind)(9-Flu)ZrCl 2 ( 2 ) and Me 2 Si(1-(4,7-Me 2 Ind))(9-Flu)ZrCl 2 ( 3 ) in the presence of methylaluminoxane (MAO) are compared. In liquid propylene at 0 °C, metallocene 2 yields a predominantly isotactic polypropylene of low tacticity ([mmmm] = 27%) where metallocene 3 produces syndiotactic polypropylene (74% [rrrr]). The stereoselectivity of metallocene 3 depends on monomer concentration: the percentage of syndiotactic pentads [rrrr] in polymers derived from 3 increases with increasing monomer concentration. Copolymerization of ethylene and propylene with metallocenes 2 and 3 yields highly alternating but atactic ethylene−propylene copolymers.

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Available abstract

The homo- and copolymerization behaviors of two C 1 -symmetric metallocenes Me 2 Si(Ind)(9-Flu)ZrCl 2 ( 2 ) and Me 2 Si(1-(4,7-Me 2 Ind))(9-Flu)ZrCl 2 ( 3 ) in the presence of methylaluminoxane (MAO) are compared. In liquid propylene at 0 °C, metallocene 2 yields a predominantly isotactic polypropylene of low tacticity ([mmmm] = 27%) where metallocene 3 produces syndiotactic polypropylene (74% [rrrr]). The stereoselectivity of metallocene 3 depends on monomer concentration: the percentage of syndiotactic pentads [rrrr] in polymers derived from 3 increases with increasing monomer concentration. Copolymerization of ethylene and propylene with metallocenes 2 and 3 yields highly alternating but atactic ethylene−propylene copolymers.

Key concepts: Tacticity, Metallocene, Methylaluminoxane, Copolymer, Monomer, Polymer chemistry, Post-metallocene catalyst, Ethylene

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Sequence and Stereoselectivity of the C1-Symmetric Metallocene Me2Si(1-(4,7-Me2Ind))(9-Flu)ZrCl2 — Research Paper | ScholarLens